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Decades of place-based, long-term ecological research have generated important insights into patterns and processes among ecosystems. Here, we extend a theoretical framework based on Odum's “strategy of ecosystem development”—which predicted distinct attributes of developing and mature ecosystems—in the context of more recent theoretical advancements that predict how long-term changes in the presses (long-term, gradual changes) and pulses (abrupt changes) of drivers that regulate ecosystem functions (press–pulse regimes) can influence their trajectories of development. Our modifications to ecosystem development theories (a) illustrate how press–pulse regimes can cause ecosystems to continue to develop or oscillate around a stable state (pulsed stability) or cause them to decline if the press–pulse regime changes faster than species and communities can adapt, (b) use examples from long-term ecological research of how attributes interact to affect development, and (c) suggest how revised and new theoretical frameworks can integrate long-term ecological research and observatory networks. [ABSTRACT FROM AUTHOR]

Abstract: Suspended sediment is an important regulator of stream habitat quality but notoriously difficult to predict and regulate. This difficulty arises because of high natural variability in suspended sediment yield in space and time. Here we quantified associations between suspended sediment yields and discharge, watershed setting (i.e., physiography and lithology), and disturbance history for 10 temperate mountain watersheds (8.5–6,242 ha) in the U.S. Pacific Northwest (H.J. Andrews Long‐Term Ecological Research, LTER) over an ~60‐year period. Annual suspended sediment yields varied almost 4 orders of magnitude across space and time. A linear mixed effects model indicated that much of the variation in yields could be explained by the random effect of site (conditional R2 = 0.74) with additional variation explained by the fixed effects (marginal R2 = 0.67) of cumulative annual discharge (p < 0.001) and the variability (standard deviation) of watershed slope (p < 0.001). Two annual sediment yield data points were model outliers, that each occurred within a decade after forest management activities and a large‐magnitude storm event at sites with high variability of catchment slope. Other sites had low sediment yields for a range of conditions, including management or flood disturbance. Taken together, our study shows that watersheds with high slope variability have higher suspended sediment yields and may be more vulnerable to increases in sediment yields following disturbances. [ABSTRACT FROM AUTHOR]

A prominent increase in the moon jellyfish (genus Aurelia ) populations has been observed since 1980 in two semi-enclosed temperate seas: the northern Adriatic Sea and the Inland Sea of Japan. Therefore, we reviewed long-term environmental and biotic data from the two Long-Term Ecological Research (LTER) sites, along with the increase in the moon jellyfish occurrence to elucidate how these coastal seas shifted to the jellyfish-dominated ecosystems. The principal component analysis of atmospheric data revealed a simultaneous occurrence of similar climatic changes in the early 1980s; thereafter, air temperature increased steadily and precipitation decreased but became more extreme. Accordingly, the average seawater temperature from March to October, a period of polyps' asexual reproduction i.e . budding, increased, potentially leading to an increase in the reproductive rates of local polyp populations. Conspicuous eutrophication occurred due to the rise of anthropogenic activities in both areas from the 1960s onwards. This coincided with an increase of the stock size of forage fishes, such as anchovy and sardine, but not the population size of the jellyfish. However, by the end of the 1980s, when the eutrophication lessened due to the regulations of nutrients loads from the land, the productive fishing grounds of both systems turned into a state that may be described as ‘jellyfish-permeated,’ as manifested by a drastic decrease in fish landings and a prominent increase in the intensity and frequency of medusa blooms. A steady increase in artificial marine structures that provide substrate for newly settled polyps might further contribute to the enhancement of jellyfish population size. Elevated fishing pressure and/or predation by jellyfish on ichthyoplankton and zooplankton might jeopardize the recruitment of anchovy, so that the anchovy catch has never recovered fully. These semi-enclosed seas may represent many temperate coastal waters with increased anthropogenic stressors, which have degraded the ecosystem from fish-dominated to jellyfish-dominated. [ABSTRACT FROM AUTHOR]

The international Long-Term Ecological Research Network (ILTER) encompasses hundreds of long-term research/monitoring sites located in a wide array of ecosystems that can help us understand environmental change across the globe. We evaluated long-term trends (1990–2015) for bulk deposition, throughfall and runoff water chemistry and fluxes, and climatic variables in 25 forested catchments in Europe belonging to the UNECE International Cooperative Programme on Integrated Monitoring of Air Pollution Effects on Ecosystems (ICP IM). Many of the IM sites form part of the monitoring infrastructures of this larger ILTER network. Trends were evaluated for monthly concentrations of non-marine (anthropogenic fraction, denoted as x) sulphate (xSO 4 ) and base cations x(Ca + Mg), hydrogen ion (H + ), inorganic N (NO 3 and NH 4 ) and ANC (Acid Neutralising Capacity) and their respective fluxes into and out of the catchments and for monthly precipitation, runoff and air temperature. A significant decrease of xSO 4 deposition resulted in decreases in concentrations and fluxes of xSO 4 in runoff, being significant at 90% and 60% of the sites, respectively. Bulk deposition of NO 3 and NH 4 decreased significantly at 60–80% (concentrations) and 40–60% (fluxes) of the sites. Concentrations and fluxes of NO 3 in runoff decreased at 73% and 63% of the sites, respectively, and NO 3 concentrations decreased significantly at 50% of the sites. Thus, the LTER/ICP IM network confirms the positive effects of the emission reductions in Europe. Air temperature increased significantly at 61% of the sites, while trends for precipitation and runoff were rarely significant. The site-specific variation of xSO 4 concentrations in runoff was most strongly explained by deposition. Climatic variables and deposition explained the variation of inorganic N concentrations in runoff at single sites poorly, and as yet there are no clear signs of a consistent deposition-driven or climate-driven increase in inorganic N exports in the catchments. [ABSTRACT FROM AUTHOR]

With an overarching goal of addressing global and regional sustainability challenges, Long Term Socio-Ecological Research Platforms (LTSER) aim to conduct place-based research, to collect and synthesize both environmental and socio-economic data, and to involve a broader stakeholder pool to set the research agenda. To date there have been few studies examining the output from LTSER platforms. In this study we enquire if the socio-ecological research from 25 self-selected LTSER platforms of the International Long-Term Ecological Research (ILTER) network has produced research products which fulfil the aims and ambitions of the paradigm shift from ecological to socio-ecological research envisaged at the turn of the century. In total we assessed 4983 publically available publications, of which 1112 were deemed relevant to the socio-ecological objectives of the platform. A series of 22 questions were scored for each publication, assessing relevance of responses in terms of the disciplinary focus of research, consideration of human health and well-being, degree of stakeholder engagement, and other relevant variables. The results reflected the diverse origins of the individual platforms and revealed a wide range in foci, temporal periods and quantity of output from participating platforms, supporting the premise that there is a growing trend in socio-ecological research at long-term monitoring platforms. Our review highlights the challenges of realizing the top-down goal to harmonize international network activities and objectives and the need for bottom-up, self-definition for research platforms. This provides support for increasing the consistency of LTSER research while preserving the diversity of regional experiences. [ABSTRACT FROM AUTHOR]

Theory predicts that interspecific tradeoffs are primary determinants of coexistence and community composition. Using information from empirically observed tradeoffs to augment the parametrisation of mechanism-based models should therefore improve model predictions, provided that tradeoffs and mechanisms are chosen correctly. We developed and tested such a model for 35 grassland plant species using monoculture measurements of three species characteristics related to nitrogen uptake and retention, which previous experiments indicate as important at our site. Matching classical theoretical expectations, these characteristics defined a distinct tradeoff surface, and models parameterised with these characteristics closely matched observations from experimental multi-species mixtures. Importantly, predictions improved significantly when we incorporated information from tradeoffs by 'snapping' characteristics to the nearest location on the tradeoff surface, suggesting that the tradeoffs and mechanisms we identify are important determinants of local community structure. This 'snapping' method could therefore constitute a broadly applicable test for identifying influential tradeoffs and mechanisms. [ABSTRACT FROM AUTHOR]

In this paper, an analysis of the interaction between the switching ripple filter components of a matrix converter-based drive and the components of a 0.4-kV electrical grid is presented. Based on the analysis, we propose a simplification of the conventional LCR filter. An inductance of the power grid transformer windings and an impedance of the power distribution lines could be considered as a filter component. Stemming from the above, a simplification of the filter topology is proposed. Only the capacitance component is necessary for realizing a conventional LCR filter. The effectiveness of this simplification is demonstrated through calculations, simulations performed in MATLAB/Simulink, and experimental results on a laboratory prototype. [ABSTRACT FROM AUTHOR]

Abstract: The Mid‐Atlantic coastal forests in Virginia are stressed by episodic disturbance from hurricanes and nor'easters. Using annual tree ring data, we adopt a dendroclimatic and statistical modeling approach to understand the response and resilience of a coastal pine forest to extreme storm events, over the past few decades. Results indicate that radial growth of trees in the study area is influenced by age, regional climate trends, and individual tree effects but dominated periodically by growth disturbance due to storms. We evaluated seven local extreme storm events to understand the effect of nor'easters and hurricanes on radial growth. A general decline in radial growth was observed in the year of the extreme storm and 3 years following it, after which the radial growth started recovering. The decline in radial growth showed a statistically significant correlation with the magnitude of the extreme storm (storm surge height and wind speed). This study contributes to understanding declining tree growth response and resilience of coastal forests to past disturbances. Given the potential increase in hurricanes and storm surge severity in the region, this can help predict vegetation response patterns to similar disturbances in the future. [ABSTRACT FROM AUTHOR]

Global change effects on biodiversity and human wellbeing call for improved long-term environmental data as a basis for science, policy and decision making, including increased interoperability, multifunctionality, and harmonization. Based on the example of two global initiatives, the International Long-Term Ecological Research (ILTER) network and the Group on Earth Observations Biodiversity Observation Network (GEO BON), we propose merging the frameworks behind these initiatives, namely ecosystem integrity and essential biodiversity variables, to serve as an improved guideline for future site-based long-term research and monitoring in terrestrial, freshwater and coastal ecosystems. We derive a list of specific recommendations of what and how to measure at a monitoring site and call for an integration of sites into co-located site networks across individual monitoring initiatives, and centered on ecosystems. This facilitates the generation of linked comprehensive ecosystem monitoring data, supports synergies in the use of costly infrastructures, fosters cross-initiative research and provides a template for collaboration beyond the ILTER and GEO BON communities. [ABSTRACT FROM AUTHOR]

Coastal dunes are fragile dynamic environments characterised by low productivity and high levels of bare and shifting sands. They are highly threatened by urbanisation and human development. The dunes in Nizzanim Dunes Nature Reserve, Israel, have additionally incurred shrub encroachment following exclusion of grazing and wood extraction from the area. The temporal changes over the last few decades have been monitored in the Nizzanim Long-Term Ecological Research project and are reflected by spatial heterogeneity. Some dunes are fixed with high plant cover and associated characteristics, while other dunes are still in semi-fixed and mobile states. Measures of beetle abundance, richness and diversity showed significant differences, among dune states. Cluster analysis and ordination of species composition revealed distinct assemblages for three different states, with more psammophilous species found in mobile dunes than in other dune states. Variation within a dune state was not significant for any dune state, while among states species composition was significantly different, demonstrating high β-diversity between dune states. Landscape heterogeneity contributes to high β-diversity and γ-diversity in the coastal dunes and continued shrub encroachment, and the associated fixation of mobile dunes will lead to habitat homogenisation and a decline in γ-diversity. This finding highlights the importance of disturbance in dynamic Mediterranean coastal dunes. We recommend a restorative intervention that promotes disturbance and heterogeneity at the landscape level by conserving all three dune states. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The nexus approach helps in recognizing the link between water, energy, and food production systems, emphasizing the need to manage them in a more integrated way. The socio-ecosystem (SES) approach, however, goes beyond that, by incorporating the regulation and supporting services in the management equation. Changes in ecosystem integrity affect the delivery of ecosystem services to society, which affects local people's well-being, creating a feedback mechanism regarding management strategies. The SES approach makes explicit the “human-bio-physical” nature of our interaction with ecosystems, highlighting the need for a more integrated and interconnected social-ecological research perspective. In addition, the SES approach makes more explicit the multi-scale character of the ecological processes that structure and maintain social-ecological systems. Water dynamics have an important role in shaping ecosystem's structure and functioning, as well as determining the systems capacity for delivering provisioning services. The tropical dry-deciduous forest (TDF), is particularly useful in studying water-food-energy trade-off interactions. Recently, a category 5 hurricane landed in the study area (Mexico's Pacific coast), triggering various social and ecological problems. This event is challenging the current forest management strategies in the region. The extreme hydrometeorological event created an excellent opportunity to test and promote the SES approach for more integrated food-water-energy research. By using the SES approach within our long-term socio-ecological research project, it was easier to identify opportunities for tackling trade-offs between maintaining the transformation of the system and a more sustainable alternative: promoting the maintenance of the ecosystem's integrity and its capacity to deliver provisioning and regulating services.

Many social-ecological system(SES)-based approaches have been proposed to address environmental problems. Most social-ecological frameworks developed to date, however, lack clear operational linkages between humans and nature to efficiently guide SESs toward resilience. A conceptual framework designed to be operational is therefore necessary, as well as a network of research platforms with which to apply it. We defined explicit coupling processes that can be used as leverages to pilot an SES toward sustainability. We proposed to formalize an SES as a dynamic entity composed of two coupling interfaces, i.e., adaptive management and ecosystem services, both set within a landscape context to provide an actionable framework. These interfaces describe the way various actors, including scholars, benefit from and manage complex and changing interactions between the biophysical and social templates. Understanding the key processes underlying the interaction dynamics, especially those leveraging adaptive management processes, would help identify adaptive pathways for practices and collective actions, provide a crucial knowledge base for policy makers, and foster operationality as a requisite of an SES research agenda. Using several examples, we explained why long-term social-ecological research platforms provide an ideal operational network of research infrastructures to conduct place-based action-orientated research targeting the sustainability of SESs.

Mountain regions are vulnerable to climate change but information about the climate sensitivity of seasonally snow-covered, subalpine ecosystems is still lacking. We investigated the impact of climatic conditions and pedogenesis on the C and N cycling along an elevation gradient under a Larch forest in the northwest (NW) Italian Alps. The environmental gradient that occurs over short distances makes elevation a good proxy for understanding the response of forest soils and nutrient cycling to different climatic conditions. Subalpine forests are located in a sensitive elevation range—the prospected changes in winter precipitation (i.e., shift of snowfalls to higher altitude, reduction of snow cover duration, etc.) could determine strong effects on soil nitrogen and carbon cycling. The work was performed in the western Italian Alps (Long-Term Ecological Research- LTER site Mont Mars, Fontainemore, Aosta Valley Region). Three sites, characterized by similar bedrock lithology and predominance of Larix decidua Mill., were selected along an elevation gradient (1550−1900 m above sea level-a.s.l.). To investigate the effects on soil properties and soil solution C and N forms of changing abiotic factors (e.g., snow cover duration, number of soil freeze/thaw cycles, intensity and duration of soil freezing, etc.) along the elevation gradient, soil profiles were opened in each site and topsoils and soil solutions were periodically collected from 2015 to 2016. The results indicated that the coldest and highest soil (well-developed Podzol) showed the highest content of extractable C and N forms (N-NH4+, DON, DOC, Cmicr) compared to lower-elevation Cambisols. The soil solution C and N forms (except N-NO3−) did not show significant differences among the sites. Independently from elevation, the duration of soil freezing, soil volumetric water content, and snow cover duration (in order of importance) were the main abiotic factors driving soil C and N forms, revealing how little changes in these parameters could considerably influence C and N cycling under this subalpine forest stand.

Long-term ecological research (LTER) sites need a periodic assessment of the state of their ecosystems and services in order to monitor trends and prevent irreversible changes. The ecological integrity (EI) framework opens the door to evaluate any ecosystem in a comparable way, by measuring indicators on ecosystem structure and processes. Such an approach also allows to gauge the sustainability of conservation management actions in the case of protected areas. Remote sensing (RS), provided by satellite, airborne, or drone-borne sensors becomes a very synoptic and valuable tool to quickly map isolated and inaccessible areas such as wetlands. However, few RS practical indicators have been proposed to relate to EI indicators for wetlands. In this work, we suggest several RS wetlands indicators to be used for EI assessment in wetlands and specially to be applied with unmanned aerial vehicles (UAVs). We also assess the applicability of multispectral images captured by UAVs over two long-term socio-ecological research (LTSER) wetland sites to provide detailed mapping of inundation levels, water turbidity and depth as well as aquatic plant cover. We followed an empirical approach to find linear relationships between UAVs spectral reflectance and the RS indicators over the Doñana LTSER platform in SW Spain. The method assessment was carried out using ground-truth data collected in transects. The resulting empirical models were implemented for Doñana marshes and can be applied for the Braila LTSER platform in Romania. The resulting maps are a very valuable input to assess habitat diversity, wetlands dynamics, and ecosystem productivity as frequently as desired by managers or scientists. Finally, we also examined the feasibility to upscale the information obtained from the collected ground-truth data to satellite images from Sentinel-2 MSI using segments from the UAV multispectral orthomosaic. We found a close multispectral relationship between Parrot Sequoia and Sentinel-2 bands which made it possible to extend ground-truth to map inundation in satellite images.

In alpine tundra the contribution of subsurface soil horizons to N and C cycling, their intraseasonal variability and soil/water interaction in the snow-free season have been poorly studied. The hypothesis that subsoil pedoclimatic factors (soil moisture and soil temperature) and nutrients (extractable N-NH 4 + , N-NO 3 − , DON, DOC, N micr and C micr ) can differ significantly from those of the topsoil was tested for 3 snow-free seasons at 3 study sites (site 1, 3 and 5) in the alpine tundra of the NW Italian Alps. In addition, the intraseasonal variability of both topsoil and subsoil extractable N and C forms was checked monthly from July to October, and they were related to those measured in the surface water of an alpine lake (Cimalegna Lake). The soil moisture did not show significant differences between topsoil and subsoil, with the exception of site 5, and was strictly correlated with the N and C forms studied at both soil depths, except for N-NO 3 − . The soil temperature was always slightly higher in the topsoil than in the subsoil, due to the incident solar irradiance, and was positively correlated with topsoil DON and C micr . At all study sites, N-NH 4 + and N-NO 3 − showed no significant differences between topsoil and subsoil, while subsoil DON, DOC, N micr and C micr significantly differed from those in the topsoil, especially at site 5. Only N-NO 3 − had a significant intraseasonal variability reaching the highest values in October at both soil depths, mainly due to the end of the plants growing season. The temporal variation of N-NO 3 − concentration observed in the lake strictly reflects the temporal changes occurred in the soils underling the fundamental role of soil biocenosis in limiting leaching losses of nitrates. [ABSTRACT FROM AUTHOR]

We tracked temporal changes in protist diversity at the Long Term Ecological Research (LTER) station MareChiara in the Gulf of Naples (Mediterranean Sea) on eight dates in 2011 using a metabarcoding approach. Illumina analysis of the V4 and V9 fragments of the 18S rDNA produced 869 522 and 1 410 071 sequences resulting in 6517 and 6519 OTUs, respectively. Marked compositional variations were recorded across the year, with less than 2% of OTUs shared among all samples and similar patterns for the two marker tags. Alveolata, Stramenopiles and Rhizaria were the most represented groups. A comparison with light microscopy data indicated an over-representation of Dinophyta in the sequence dataset, whereas Bacillariophyta showed comparable taxonomic patterns between sequence and light microscopy data. Shannon diversity values were stable from February to September, increasing thereafter with a peak in December. Community variance was mainly explained by seasonality (as temperature), trophic status (as chlorophyll a), and influence of coastal waters (as salinity). Overall, the background knowledge of the system provided a sound context for the result interpretation, showing that LTER sites provide an ideal setting for high-throughput sequencing (HTS) metabarcoding characterisation of protist assemblages and their relationships with environmental variations. [ABSTRACT FROM AUTHOR]

Species turnover is a key parameter influencing dynamics of species in a community. Here I explore relationships between temporal species turnover and productivity and between temporal species turnover and richness in an abandoned pasture in Puerto Rico. Permanent plot data collected in the pasture over the first 10 years after abandonment were used to generate linear regressions, which were then used to test two hypotheses about how productivity and richness relate to turnover, as this pasture reverts back to rainforest. I found (1) productivity had a slight positive relationship (small positive slope) with turnover in years two and three after abandonment, but a large negative relationship (large negative slope) in year four and afterwards, and (2) richness had a negative relationship with turnover in every year which increased (slope became more negative) with time. Because both productivity and richness had a negative relationship with turnover, species loss decreased with time even when species productivity and richness continued to increase or level off; turnover consists mainly in the loss of less productive species. I suggest restoration strategies that managers may follow to either increase or decrease that most basic successional parameter, turnover. [ABSTRACT FROM AUTHOR]

Salt marshes are among the most productive ecosystems on Earth, providing nurseries for fish species and shelter and food for endangered birds. Salt marshes also mitigate the impacts of hurricanes and tsunamis, and sequester large volumes of carbon in their peat soil. Understanding the mechanisms responsible for marsh stability or deterioration is therefore a key issue for society. Sea level rise is often viewed as the main driver of salt marsh deterioration. However, while salt marshes can reach equilibrium in the vertical direction, they are inherently unstable in the horizontal direction. Marsh expansion driven by sediment supply rarely matches lateral erosion by waves, creating a dynamic landscape. Recent results show that marsh collapse can occur in the absence of sea level rise if the rate at which sediment is eroded at marsh boundaries is higher than the input of sediment from nearby rivers or from the continental shelf. We propose that the horizontal dynamics and related sediment fluxes are key factors determining the survival of salt marshes. Only a complete sediment budget between salt marshes and nearby tidal flats can determine the fate of marshes at any given location, with sea level rise being only one among many external drivers. Ancient Venetians understood this dynamic very well. They manipulated the supply of sediment to the Venice lagoon, Italy, in order to control the long-term evolution of the intertidal landscape.

The US National Science Foundation's Long Term Ecological Research (LTER) network was established in 1980 to provide the scientific expertise, research platforms, and long-term data sets necessary to document and analyze environmental change (http://www.lternet.edu). There are currently 25 sites in the US LTER network representing a range of ecosystems, including deserts, prairies, forests, tundra, lakes, urban areas, estuaries, coastal reefs, the pelagic ocean, and production agriculture. Although the research questions being addressed vary across the network, each site collects data on primary production, population dynamics, the cycling of both organic and inorganic matter, and disturbance patterns. Long-term data in these core areas enable changes in critical ecological processes to be tracked over time and facilitate comparisons among different ecosystem types.

Simultaneous measurement of the gross and net primary production of the benthic community and the net input of organic carbon delivered by currents to the coral reef flat of the north shore of Moorea, French Polynesia, confirms that carbon fixation by bottom-dwelling autotrophs, including algal symbionts in corals and benthic free-living algae, is the major source of new organic matter to this system. However, particulate organic carbon, including plankton, detritus, and macroalgal fragments originating primarily on the fore reef and reef crest and carried onto the reef flat by currents contributes up to 13% of the net organic carbon input to the zone nearest the reef crest. These results are typical of the many reef flats worldwide that experience unidirectional flow.

Salt marshes often contain remarkable spatial heterogeneity at multiple scales across the landscape. A combination of advanced remote-sensing approaches (hyperspectral imagery and lidar) and conventional field survey methods was used to produce detailed quantifications and maps of marsh platform geomorphology, vegetation composition and biomass, and invertebrate patterns in a Georgia (USA) salt marsh. Community structure was largely related to hydrology, elevation, and soil properties. Both abiotic drivers and community patterns varied among subwatersheds and across the landscape at larger spatial scales. The authors conclude that measurements of marsh ecosystem structure and processes are spatially contextual and not scalable without detailed geospatial analysis. Efforts to protect and restore coastal marshes must strive to document, understand, and conserve this inherent spatial complexity.

Forests of the giant kelp Macrocystis pyrifera found on coastal rocky reefs lack the large reservoirs for nutrient storage found in many terrestrial environments. Supporting their high year-round growth rates requires a continuous supply of nitrogen. Complementary timing of nutrient supply associated with the physical processes that deliver nitrate to reefs largely achieves this goal, but modeling studies indicate that the magnitude of nitrate delivery is inadequate to support the measured nitrogen demand of kelp forests during summer. Ammonium, from sediment efflux and excretion by reef consumers, likely fills the deficit. Together, the varied sources of inorganic nitrogen supplied to kelp forests support their high growth rates throughout the year. Kelp compensates for diminished nitrogen supply during summer by decreasing tissue nitrogen content, resulting in a doubling of kelp C:N ratios.

Tide propagation through coastal wetlands is a complex phenomenon affected by vegetation, channels, and tidal conditions. Generally, tidal flow is studied using stage (water level) observations, which provide good temporal resolution, but they are acquired in limited locations. Here, a remote-sensing technique, wetland InSAR (interferometric synthetic aperture radar), is used to detect tidal flow in vegetated coastal environments over broad spatial scales. The technique is applied to data sets acquired by three radar satellites over the western Everglades in south Florida. Interferometric analysis of the data shows that the greatest water-level changes occur along tidal channels, reflecting a high velocity gradient between fast horizontal flow in the channel and the slow flow propagation through the vegetation. The high-resolution observations indicate that the tidal flushing zone extends 2–3 km on both sides of tidal channels and can extend 3–4 km inland from the end of the channel. The InSAR observations can also serve as quantitative constraints for detailed coastal wetland flow models.

Ten years of oceanic and meteorological monitoring data were collected in order to understand the spatial and temporal patterns of salinity distribution across three adjacent estuaries in the Georgia Coastal Ecosystems Long Term Ecological Research domain. Empirical orthogonal function analysis shows that 95% of the subtidal salinity variability can be explained by two principle modes. The first mode is dominated by river discharge, and causes system-wide freshening throughout the domain. The second mode, which explains 8% of the variability, is correlated with subtidal sea surface height and, hence, alongshore winds. The response in Sapelo and Doboy Sounds to this second mode, however, is out of phase with that of Altamaha Sound. During upwelling-favorable winds when coastal sea surface height decreases, Altamaha Sound freshens, and salinity increases in Doboy and Sapelo Sounds. On the other hand, freshening in Doboy and Sapelo Sounds and a salinity increase in Altamaha Sound accompany downwelling-favorable winds. A regional ocean model of a highly idealized coastal domain of three adjacent estuaries connected by the Intracoastal Waterway is consistent with the observations—river discharge and upwelling-favorable winds freshen the coastal domain so that when downwelling-favorable winds occur, the coastal freshwater originating in the Altamaha River is transported into Sapelo and Doboy Sounds. Model results suggest that the Intracoastal Waterway and the complex network of channels that connects the sounds play a dominant role in water exchange between the adjacent estuaries.

The dynamics of shallow-water coastal environments are controlled by external drivers—sea level rise, storms, and sediment and nutrient supplies—and by internal feedbacks. Interactions of biotic processes (vegetation growth, trophic dynamics) and abiotic drivers can lead to nonlinear responses to changing conditions and to the emergence of thresholds, hysteresis, and alternative stable states. We develop a conceptual framework for studying interactions between the dynamics of marshes and habitats in shallow coastal bays with unconsolidated sediments (seagrass, oyster reefs). Using examples primarily from the Virginia Coast Reserve Long Term Ecological Research site, we show that in the subtidal part of the landscape, two alternative stable states can exist—one dominated by seagrass up to a certain depth that represents a tipping point to the second, unvegetated stable state. The depth limit of the seagrass stable state is influenced by (1) the positive feedback of vegetation on reducing sediment suspension and improving the light environment for growth, (2) climate (e.g., temperature), and (3) water quality. Two stable states are also present in intertidal areas, with salt marshes lying above mean sea level and tidal flats below mean sea level. State transitions are driven by sediment availability, sea level rise, the relative strength of wind waves with respect to tidal currents, and the biotic feedback of vegetation on sediment stabilization and accretion. State-change dynamics in one system may propagate to adjacent systems, and this coupling may influence the landscape-scale response to environmental change. Seagrass meadows and oyster reefs affect adjacent marshes both positively (wave attenuation) and negatively (reduced sediment supply), and marsh-edge erosion could negatively influence the light environment for seagrass growth. Forecasting the resilience of coastal ecosystems and the landscape-scale response to environmental change in the next century requires an understanding of nonlinear dynamics, including the possibility of multiple stable states, the coupled evolution of adjacent systems, and potential early warning signs of thresholds of change.

The Moorea Coral Reef Long Term Ecological Research project funded by the US National Science Foundation includes multidisciplinary studies of physical processes driving ecological dynamics across the fringing reef, back reef, and fore reef habitats of Moorea, French Polynesia. A network of oceanographic moorings and a variety of other approaches have been used to investigate the biological and biogeochemical aspects of water transport and retention processes in this system. There is evidence to support the hypothesis that a low-frequency counterclockwise flow around the island is superimposed on the relatively strong alongshore currents on each side of the island. Despite the rapid flow and flushing of the back reef, waters over the reef display chemical and biological characteristics distinct from those offshore. The patterns include higher nutrient and lower dissolved organic carbon concentrations, distinct microbial community compositions among habitats, and reef assemblages of zooplankton that exhibit migration behavior, suggesting multigenerational residence on the reef. Zooplankton consumption by planktivorous fish on the reef reflects both retention of reef-associated taxa and capture by the reef community of resources originating offshore. Coral recruitment and population genetics of reef fishes point to retention of larvae within the system and high recruitment levels from local adult populations. The combined results suggest that a broad suite of physical and biological processes contribute to high retention of externally derived and locally produced organic materials within this island coral reef system.

The paucity of data on migratory connections and an incomplete understanding of how mobile organisms use geographically separate areas have been obstacles to understanding coastal dynamics. Research on acoustically tagged striped bass (Morone saxatilis) at the Plum Island Ecosystems (PIE) Long Term Ecological Research site, Massachusetts, documents intriguing patterns of biotic connectivity (i.e., long-distance migration between geographically distinct areas). First, the striped bass tagged at PIE migrated southward along the coast using different routes. Second, these tagged fish exhibited strong fidelity and specificity to PIE. For example, across multiple years, tagged striped bass resided in PIE waters for an average of 1.5–2.5 months per year (means: 51–72 days; range 2–122 days), left this estuary in fall, then returned in subsequent years. Third, this specificity and fidelity connected PIE to other locations. The fish exported nutrients and energy to at least three other coastal locations through biomass added as growth. These results demonstrate that what happens in an individual estuary can affect other estuaries. Striped bass that use tightly connected routes to feed in specific estuaries should have greater across-system impacts than fish that are equally likely to go anywhere. Consequently, variations in when, where, and how fish migrate can alter across-estuary impacts.

Terrestrial inputs largely govern nutrient delivery to the coastal ocean, and subsequent processes transform these nutrients in the land-ocean transition zone. Here, we describe spatial and temporal patterns in surface water chemistry from the Duplin, a salt marsh/tidal creek system located in coastal Georgia, USA. Key drivers of nutrient concentration patterns in the Duplin include discharge from the nearby Altamaha River, groundwater inputs, exchange with the marsh platform, and biological processes within the tidal creek. Altamaha River discharge is correlated with salinity in the Duplin, but the processes taking place within the Duplin watershed regulate the distribution of other dissolved and particulate materials. Long-term data sets advance our understanding of the relative importance of these processes in generating the observed patterns in surface water chemistry. This knowledge improves our ability to predict how coastal systems will respond to anthropogenic perturbations.

The Moorea Coral Reef Long Term Ecological Research program affords a unique opportunity to study the implications of ocean acidification (OA) for coral reefs, as ongoing ecological and physical monitoring there provides a context in which the patterns of community change attributed to OA can be detected. We used mesocosms to study the impacts of OA on corals and calcified algae, and conducted experiments to compare multiple species and evaluate how they are affected by changing concentrations of the different forms of dissolved inorganic carbon. Our results reveal taxonomic variation in the response to OA, with some corals and algae showing signs of resistance to OA conditions. This discovery is informing an urgent debate over the form in which coral reefs will survive (if at all) in the future.

Understanding the effects of climate change on planktonic ecosystems requires the synthesis of large, diverse data sets of variables that often interact in nonlinear ways. One fruitful approach to this synthesis is the use of numerical models. Here, we describe how models have been used to gain understanding of the physical-biological couplings leading to decadal changes in the southern California Current ecosystem. Moving from basin scales to local scales, we show how atmospheric, physical oceanographic, and biological dynamics interact to create long-term fluctuations in the dynamics of the California Current ecosystem.

Event-scale phenomena, of limited temporal duration or restricted spatial extent, often play a disproportionately large role in ecological processes occurring in the ocean water column. Nutrient and gas fluxes, upwelling and downwelling, transport of biogeochemically important elements, predator-prey interactions, and other processes may be markedly influenced by such events, which are inadequately resolved from infrequent ship surveys. The advent of autonomous instrumentation, including underwater gliders, profiling floats, surface drifters, enhanced moorings, coastal high-frequency radars, and satellite remote sensing, now provides the capability to resolve such phenomena and assess their role in structuring pelagic ecosystems. These methods are especially valuable when integrated together, and with shipboard calibration measurements and experimental programs.

The extent, duration, and seasonality of sea ice and glacial discharge strongly influence Antarctic marine ecosystems. Most organisms' life cycles in this region are attuned to ice seasonality. The annual retreat and melting of sea ice in the austral spring stratifies the upper ocean, triggering large phytoplankton blooms. The magnitude of the blooms is proportional to the winter extent of ice cover, which can act as a barrier to wind mixing. Antarctic krill, one of the most abundant metazoan populations on Earth, consume phytoplankton blooms dominated by large diatoms. Krill, in turn, support a large biomass of predators, including penguins, seals, and whales. Human activity has altered even these remote ecosystems. The western Antarctic Peninsula region has warmed by 7°C over the past 50 years, and sea ice duration has declined by almost 100 days since 1978, causing a decrease in phytoplankton productivity in the northern peninsula region. Besides climate change, Antarctic marine systems have been greatly altered by harvesting of the great whales and now krill. It is unclear to what extent the ecosystems we observe today differ from the pristine state.

Wind-driven upwelling is weak and intermittent in the Southern California Bight, a region sheltered from the strong, prevailing equatorward winds typical of most of the California Current System. Thus, other physical transport processes than wind-driven upwelling supply subsidies of nutrients, biogenic particles, and other water-borne materials to support the highly productive temperate reef ecosystems of the Southern California Bight, including forests of giant kelp (Macrocystis pyrifera) and a broad diversity of reef organisms. This article focuses on results from the Santa Barbara Coastal Long Term Ecological Research project related to the various transport processes important for maintaining nearshore ecosystems in the California Current System. It reviews along-shelf and cross-shelf flow mechanisms that deliver these subsidies, discusses how these mechanisms interact, and examines some of the biological patterns that result from these transport processes.

Recent studies suggest that coastal ecosystems can bury significantly more C than tropical forests, indicating that continued coastal development and exposure to sea level rise and storms will have global biogeochemical consequences. The Florida Coastal Everglades Long Term Ecological Research (FCE LTER) site provides an excellent subtropical system for examining carbon (C) balance because of its exposure to historical changes in freshwater distribution and sea level rise and its history of significant long-term carbon-cycling studies. FCE LTER scientists used net ecosystem C balance and net ecosystem exchange data to estimate C budgets for riverine mangrove, freshwater marsh, and seagrass meadows, providing insights into the magnitude of C accumulation and lateral aquatic C transport. Rates of net C production in the riverine mangrove forest exceeded those reported for many tropical systems, including terrestrial forests, but there are considerable uncertainties around those estimates due to the high potential for gain and loss of C through aquatic fluxes. C production was approximately balanced between gain and loss in Everglades marshes; however, the contribution of periphyton increases uncertainty in these estimates. Moreover, while the approaches used for these initial estimates were informative, a resolved approach for addressing areas of uncertainty is critically needed for coastal wetland ecosystems. Once resolved, these C balance estimates, in conjunction with an understanding of drivers and key ecosystem feedbacks, can inform cross-system studies of ecosystem response to long-term changes in climate, hydrologic management, and other land use along coastlines.

Until recently, it was believed that biological assimilation and gaseous nitrogen (N) loss through denitrification were the two major fates of nitrate entering or produced within most coastal ecosystems. Denitrification is often viewed as an important ecosystem service that removes reactive N from the ecosystem. However, there is a competing nitrate reduction process, dissimilatory nitrate reduction to ammonium (DNRA), that conserves N within the ecosystem. The recent application of nitrogen stable isotopes as tracers has generated growing evidence that DNRA is a major nitrogen pathway that cannot be ignored. Measurements comparing the importance of denitrification vs. DNRA in 55 coastal sites found that DNRA accounted for more than 30% of the nitrate reduction at 26 sites. DNRA was the dominant pathway at more than one-third of the sites. Understanding what controls the relative importance of denitrification and DNRA, and how the balance changes with increased nitrogen loading, is of critical importance for predicting eutrophication trajectories. Recent improvements in methods for assessing rates of DNRA have helped refine our understanding of the rates and controls of this process, but accurate measurements in vegetated sediment still remain a challenge.

During recent human history, human activities such as overhunting and habitat destruction have severely impacted many large top predator populations around the world. Studies from a variety of ecosystems show that loss or diminishment of top predator populations can have serious consequences for population and community dynamics and ecosystem stability. However, there are relatively few studies of the roles of large top predators in coastal ecosystems, so that we do not yet completely understand what could happen to coastal areas if large top predators are extirpated or significantly reduced in number. This lack of knowledge is surprising given that coastal areas around the globe are highly valued and densely populated by humans, and thus coastal large top predator populations frequently come into conflict with coastal human populations. This paper reviews what is known about the ecological roles of large top predators in coastal systems and presents a synthesis of recent work from three coastal eastern US Long Term Ecological Research (LTER) sites where long-term studies reveal what appear to be common themes relating to the roles of large top predators in coastal systems. We discuss three specific themes: (1) large top predators acting as mobile links between disparate habitats, (2) large top predators potentially affecting nutrient and biogeochemical dynamics through localized behaviors, and (3) individual specialization of large top predator behaviors. We also discuss how research within the LTER network has led to enhanced understanding of the ecological roles of coastal large top predators. Highlighting this work is intended to encourage further investigation of the roles of large top predators across diverse coastal aquatic habitats and to better inform researchers and ecosystem managers about the importance of large top predators for coastal ecosystem health and stability.

The southern California Current Ecosystem (CCE) is a dynamic eastern boundary current ecosystem that is forced by ocean-atmosphere variability on interannual, multidecadal, and long-term secular time scales. Recent evidence suggests that apparent abrupt transitions in ecosystem conditions reflect linear tracking of the physical environment rather than oscillations between alternative preferred states. A space-for-time exchange is one approach that permits use of natural spatial variability in the CCE to develop a mechanistic understanding needed to project future temporal changes. The role of (sub)mesoscale frontal systems in altering rates of nutrient transport, primary and secondary production, export fluxes, and the rates of encounters between predators and prey is an issue central to this pelagic ecosystem and its future trajectory because the occurrence of such frontal features is increasing.

Feedbacks between flooding and plant growth that help to stabilize marshes against rising sea level are being investigated in estuaries at Plum Island, Massachusetts, and North Inlet, South Carolina. Net annual primary production of the marsh grass Spartina alterniflora has been quite variable through the years, and correlates positively with sea level during the growing season at both sites. The elevation of the marsh surface relative to mean high water determines the duration of flooding, or hydroperiod, that in turn affects plant growth. The effect of flooding was tested experimentally using an in situ bioassay to simulate growth at different relative elevations. At North Inlet, we found a parabolic response to relative elevation, with clear evidence of minimum and maximum vertical limits and an optimal elevation for growth. The Plum Island bioassay provided evidence of the super-optimal side of the growth curve. In both marshes, the responses of S. alterniflora to rising sea level, at their current elevations, are consistent with the bioassay results. This growth curve is important because it defines suboptimal elevations that are unstable for marshes and super-optimal elevations that are stable. Instability results when an increase in sea level decreases primary production, leading to declines in mineral sedimentation and sediment organic matter accretion. Conversely, stability results when rising sea level stimulates primary production, leading to increased sedimentation and organic matter accretion. There also has been interannual variability in the maximum standing biomass (a proxy for productivity) of another marsh grass, Spartina patens, but no significant correlation has been found with sea level, possibly due to methodological limitations. Finally, both Spartina species responded positively to nitrogen and have remained highly productive for 13 years of fertilization at Plum Island and 30 years at North Inlet.

Research programs that co-locate environmental sensors with "biology" can enable the linking of environmental data with changes in biological or ecological processes. The coastal and marine Long Term Ecological Research (LTER) programs use this strategy, measuring parameters such as air and sea temperature, wave and storm energy, and seawater chemistry along with biological responses to them. This investment in technology has proven to be valuable and a major scientific asset for understanding how climate change, and environmental change in general, might alter marine populations and communities. Such a strategy can also aid in studies of global change biology of critical species, helping to place laboratory experiments and predictions of response in a broader environmental context. This coupling of long-term physical and biological observations has already detected fingerprints of change in sites such as the Palmer LTER situated on the western Antarctic Peninsula. In addition, new autonomous pH sensors recently deployed at two marine LTERs—Santa Barbara Coastal and Moorea Coral Reef—are generating long-term data sets that highlight the responses of their marine communities to rapidly changing ocean conditions.

Climate change is affecting the ecosystems and the services they provide for human wellbeing. For a better understanding of the causes and effects of this change in the functioning of ecosystems, detailed information of environmental parameters needs to be considered. Researchers generate multiple databases in their academic disciplines but often this data collection is not openly available nor does it fulfill the FAIR principles of Findability, Accessibility, Interoperability, and Reusability (Wilkinson et al. 2016). In this regard, Long-Term Ecosystem Research (LTER) plays an important role as an open research infrastructure that helps to integrate in-situ data, remote sensing products and modelling efforts, related to biodiversity and geodiversity. Within LTER networks, the Dynamic Ecological Information Management System – Site and Dataset Registry (DEIMS-SDR), is used as the central site catalogue to provide information about facilities, ecosystems and environmental parameters in an openly available and standardized way (Wohner et al. 2019), organized by each location's site. These LTER sites from all around the globe, receive a special protection status due to their ecological value, which through research and observation, enhances the protection and conservation of these areas. The LTER Ria de Aveiro site in Portugal (DEIMS.ID; LTER website), classified under the Natura 2000 network, is of paramount importance for the regional and national economy, agriculture, commercial fisheries, aquaculture, manufacturing, tourism, sports and recreational activities (e.g. Lillebø et al. 2019). Since the establishment of the LTER Ria de Aveiro site in 2011, its research has focused on the contribution to the effective implementation of the Water Framework Directive and European Union Biodiversity Strategy targets. Studies have been developed to target key policies within Natura 2000 areas, Action 5 including habitat mapping and assessment of ecosystems and their services, data collection of important fauna groups, and engagement of stakeholders and common frameworks for the conservation of biodiversity. Currently, the site is part of the Portuguese e-Infrastructure for Information and Research on Biodiversity (PORBIOTA), being aligned with the European Research Infrastructure Consortium (LifeWatch-ERIC). The LTER site team infrastructure includes laboratory facilities for field observation and environmental monitoring of water quality and environmental parameters that are used to feed models. A recently obtained Unmanned Aerial Vehicle (UAV), commonly known as drone, will contribute to ecological observations, generating data to provide biodiversity monitoring in space and time. As LTER site managers and data providers, we have to deal with how to make the transition from our metadata to FAIR ecological data. Our aim is to deal with the implementation of standardized data profiles in our own data. For instance, to upload data files to the central repositories (e.g. DEIMS-SDR), to store and publish our raw data (e.g. B2Share), to create online distribution links and digital object identifiers (DOIs), and to use a convenient vocabulary (e.g. Environmental Thesaurus) to be understandable by everyone (Pérez-Luque et al. 2019). This substantially will increase the potential of databases in the scientific community, and will contribute to a successful building of LTER. [ABSTRACT FROM AUTHOR]

DEIMS-SDR (Dynamic Ecological Information Management System - Site and dataset registry, Wohner et al. 2019) is one of the largest repositories of long-term ecological research (LTER) datasets. It provides sophisticated searching tools by metadata elements and identifiers for all the 930 contained datasets, most of them from European sites. Whereas datasets' metadata are highly structured and searchable, datasets themselves have little standardization in terms of content, identifiers or license, making data integration difficult or cumbersome. Adopting the data FAIR guiding principles(Wilkinson et al. 2016) for LTER data would result in better data integration and reutilization to support knowledge discovery and innovation in ecological research. The Global Biodiversity Information Facility (GBIF 2019a). is the largest repository of species distribution data in the world, providing access to more than a billion records from over 43,000 datasets. GBIF is a good example of FAIR principles implementation: GBIF data is highly standardized, using Darwin Core (Wieczorek et al. 2012) for data and ecological metadata language (EML, Fegraus et al. 2005) for metadata, allowing recordlevel search; and has implemented globally unique and persistent identifiers for datasets and downloads. Relevant in this context is that GBIF has recently introduced a new data format intended for monitoring projects and sampling event protocols (GBIF 2019b). In this presentation, we explore the suitability of GBIF data formats and workflows to serve LTER datasets, and the work it may take to transform typical LTER datasets into these formats. For this exercise, we use some datasets available via the DEIMS platform, corresponding to the same territory, (Sierra Nevada, Spain (e.g. Bonet 2016, Bonet 2018) and transform them into the GBIF's sample-based Event core publish them in the GBIF data network, and then perform an analysis to assess how the standardized datasets work in practice, both among themselves and also with typical "occurrence-based" GBIF datasets. Finally, we discuss our findings and make recommendations for the GBIF and LTER communities. [ABSTRACT FROM AUTHOR]

Desde su inicio formal en 1980, los programas de investigación ecológica a largo plazo (LTER por su sigla en inglés) han servido como un exitoso marco organizacional para crear agendas de investigación y mecanismos de financiamiento que permiten a los científicos abordar fenómenos ecológicos significativos a las escalas en que ellos ocurren. En sus 30 años de existencia, LTER ha expandido su rango geográfico (actualmente la red Internacional de LTER tiene más de 40 países miembros con sitios de estudios en cada uno de los continentes) y focos disciplinarios (principalmente abarcando las ciencias naturales y sociales, llevando a algunos a pedir un cambio de nombre a estudios de investigación socioecológica de largo plazo - LTSER por su sigla en inglés). No obstante, los biomas templados y subantárticos del sur de Sudamérica han carecido de sitios y redes formales de investigación a largo plazo. Sin embargo, numerosos esfuerzos de investigación a largo plazo han existido en Chile y Argentina sin coordinación entre sí. Particularmente, en 2008, el Instituto de Ecología y Biodiversidad puso en marcha el primer esfuerzo sistemático para articular tres sitios existentes (Parque Nacional Fray Jorge - 33° S, Estación Biológica Senda Darwin - 43° S, y Parque Etnobotánico Omora - 55° S). Aquí presentamos un número especial de la Revista Chilena de Historia Natural, dedicado a LTSER, con el objetivo de 1) dar una síntesis de algunos de los casos más emblemáticos casos de investigación socioecológica a largo plazo en Chile; 2) demostrar el valor de estos esfuerzos para la integración de la investigación y educación con resultados y procesos sociales, tales como aquellos relacionados con la toma de decisiones; y 3) ofrecer la perspectiva de una amplia gama de participantes involucrados en estas iniciativas, incluyendo a estudiantes de postgrado y programas asociados desde Iberoamérica y Norteamérica. Es nuestro deseo que estos trabajos compilados contribuyan a la consolidación de la aproximación de LTSER en el sur de Sudamérica dentro de la comunidad académica y también para una mayor integración entre la academia y la sociedad.Since their formal inception in 1980, long-term ecological research (LTER) programs have served as a successful organizing framework to create research agendas and funding mechanisms that allow scientists to address meaningful ecological phenomena at the scales they occur. In its 30 years of existence, LTER has expanded its geographic range (currently the International LTER network has more than 40 country members with sites on every continent) and disciplinary foci (principally encompassing the natural and social sciences and leading some to call for a name change to long-term socio-ecological research - LTSER). Nonetheless, the temperate and subantarctic biomes of southern South America have lacked formalized long-term research sites and networks. Yet, at the same time, numerous uncoordinated long-term research efforts exist in both Chile and Argentina, and in 2008, the Institute of Ecology and Biodiversity launched Chile’s first concerted effort to link three existing sites (Fray Jorge Forest National Park - 33° S, Senda Darwin Biological Station - 43° S, and Omora Ethnobotanical Park - 55° S). Here, we present a special feature of the Revista Chilena de Historia Natural, dedicated to LTSER, with the aim of 1) providing a synthesis of some of the most emblematic cases of long-term socio-ecological research in Chile; 2) demonstrating the value of these efforts for the integration of research, education and social outcomes, such as decision making; and 3) offering the perspective of a broad array of participants involved in these initiatives, including graduate students and associated programs from Ibero-America and North America. It is our hope that these compiled works will contribute to the consolidation of the LTSER approach in southern South America both within the academic community and also to better link academia and society.

Since 1989, we have conducted a large-scale ecological experiment in semiarid thorn scrub of a national park in north-central Chile. Initially, we focused on the role of biotic interactions including predation, interspecific competition, and herbivory in small mammal and plant components of the community. We utilized a reductionist approach with replicated 0.56 ha fenced grids that selectively excluded vertebrate predators and/or larger small mammal herbivores such as the degu, Octodon degus. Although we detected small transitory effects of predator exclusions on degu survival and numbers, other species failed to show responses. Similarly, interspecific competition (i.e., degus with other small mammals) had no detectable numerical effects (although some behavioral responses occurred), and degu-exclusions had relatively small effects on various plant components. Modeling approaches indicate that abiotic factors play a determining role in the dynamics of principal small mammal species such as O. degus and the leaf-eared mouse (Phyllotis darwini). In turn, these are mainly related to aperiodic pulses of higher rainfall (usually during El Niño events) which trigger ephemeral plant growth; a food addition experiment in 1997-2000 verified the importance of precipitation as a determinant of food availability. Since 2004, we have expanded long-term monitoring efforts to other important community components including birds and insects in order to understand effects of abiotic factors on them; we report some of the first results of comprehensive surveys on the former in this region. Finally, we recently shifted focus to documenting effects of exotic lagomorphs in the park. We installed additional treatments selectively excluding small mammals, lagomorphs, or both, from replicated grids in order to evaluate putative herbivore impacts. In conjunction with increased annual rainfall since 2000, we predict that introduced lagomorphs will have increasing impacts in this region, and that more frequent El Niños in conjunction with global climatic change may lead to marked changes in community dynamics. The importance of long-term experimental studies is underscored by the fact that only now after 20 years of work are some patterns becoming evident.Desde 1989 hemos llevado a cabo un experimento ecológico a gran escala en un matorral espinoso semiárido de un parque nacional en el norte de Chile. Inicialmente, nos centramos en el rol de las interacciones bióticas incluyendo depredación, competencia interespecífica y herbivoría en micromamíferos y componentes vegetales de la comunidad. Usamos una aproximación reduccionista con parcelas replicadas cercadas de 0.56 ha que selectivamente excluían depredadores vertebrados y/o micromamíferos herbívoros más grandes como el degu, Octodon degus. Aunque detectamos efectos transitorios menores en la sobrevivencia y número de degus en las exclusiones de depredadores, otras especies no mostraron respuestas. Similarmente, la competencia interespecífica (i.e., degus con otros micromamíferos) no tenía efectos numéricos detectables (aunque ocurrieron algunas respuestas conductuales), y las exclusiones tuvieron efectos relativamente pequeños en varios componentes vegetales. Aproximaciones basadas en modelos indican que los factores abióticos juegan un papel determinante en la dinámica de las especies de micromamíferos principales como O. degus y la laucha orejuda (Phyllotis darwini). En cambio, estos están principalmente relacionados a pulsos no periódicos de lluvias más altas (usualmente durante los eventos El Niño) que gatilla el crecimiento de plantas efímeras; un experimento de adición de alimento en 1997-2000 verificó la importancia de la precipitación como un determinante de la disponibilidad de alimento. Desde el 2004 hemos expandido los esfuerzos de monitoreo de largo plazo a otros componentes comunitarios importantes incluyendo aves e insectos con el fin de entender los efectos de los factores abióticos sobre ellos; informamos algunos de los primeros resultados de censos comprehensivos de aves en esta región. Finalmente, hace poco cambiamos de foco para documentar el efecto de lagomorfos exóticos en el parque. Instalamos tratamientos adicionales excluyendo selectivamente micromamíferos, lagomorfos, o ambos, de parcelas replicadas con el fin de evaluar impactos de herbívoros. En conjunto con el aumento de la precipitación anual desde 2000, predecimos que los lagomorfos introducidos tendrán mayores impactos en esta región y que más frecuentes El Niño en combinación con el cambio climático global puede conducir a cambios marcados en la dinámica comunitaria. La importancia de experimentos de largo plazo es destacado por el hecho que solamente ahora después de 20 años de trabajo algunos patrones están siendo evidentes.

Atmospheric nitrogen (N) pollution is considered responsible for a substantial decline in plant species richness and for altered community structures in terrestrial habitats worldwide. Nitrogen affects habitats through direct toxicity, soil acidification, and in particular by favoring fast-growing species. Pressure from N pollution is decreasing in some areas. In Europe (EU28), overall emissions of NO _x declined by more than 50% while NH _3 declined by less than 30% between the years 1990 and 2015, and further decreases may be achieved. The timescale over which these improvements will affect ecosystems is uncertain. Here we use 23 European forest research sites with high quality long-term data on deposition, climate, soil recovery, and understory vegetation to assess benefits of currently legislated N deposition reductions in forest understory vegetation. A dynamic soil model coupled to a statistical plant species niche model was applied with site-based climate and deposition. We use indicators of N deposition and climate warming effects such as the change in the occurrence of oligophilic, acidophilic, and cold-tolerant plant species to compare the present with projections for 2030 and 2050. The decrease in N deposition under current legislation emission (CLE) reduction targets until 2030 is not expected to result in a release from eutrophication. Albeit the model predictions show considerable uncertainty when compared with observations, they indicate that oligophilic forest understory plant species will further decrease. This result is partially due to confounding processes related to climate effects and to major decreases in sulphur deposition and consequent recovery from soil acidification, but shows that decreases in N deposition under CLE will most likely be insufficient to allow recovery from eutrophication.

Based on biological and meteorological long-term database (1979-1983 and 1996-2000), we analyzed the variation in the juvenile recruitment and artisanal fishery landings of the mullet (Mugil platanus) in the Patos Lagoon estuary and its relationships with the regional rainfall and estuarine salinity anomalies during two strong El Niño events (1982-83 and 1997-98). Juvenile and adult mullets declined in abundance under the high rainfall and near-zero salinity that prevailed in the estuary during both El Niño events. We proposed two different hypotheses to explain the El Niño-induced effects on the juvenile and adult stages of the mullet in the estuary. First, high freshwater outflow during a very strong El Niño might render ineffective the mechanism of passive immigration of juvenile mullets into the estuary, which can lead to their decline in the estuary during El Niño events. Second, near-zero salinity at the estuarine area along several months during strong El Niño events could lead to higher spatial dispersion of the maturing mullet during their migration to the ocean , resulting in smaller shoals of individuals and, consequently, lower catches by artisanal fishermen.Episódios El Niño ocorrem na região tropical do Oceano Pacífico e estão associados com o aumento da descarga continental de água na Lagoa dos Patos (10.360 km²) e sua região estuarina (971 km²). A partir de um banco de dados meteorológicos e biológicos de longo prazo (1979-1983 e 1996-2000), este trabalho investiga as variações no recrutamento de juvenis e no desembarque da pesca artesanal da tainha (Mugil platanus) no estuário da Lagoa dos Patos e suas relações com anomalias regionais de chuva e anomalias locais de salinidade durante dois fortes episódios El Niño (1982-1983 e 1997-1998). Tanto os juvenis quanto a captura dos adultos na pesca artesanal diminuíram em abundância durante as chuvas excessivas e salinidades próximas a zero que prevaleceram no estuário durante ambos eventos climáticos. Duas hipóteses são sugeridas para explicar os efeitos ocasionados pelo El Niño sobre as fases juvenis e adultas da tainha no estuário da Lagoa dos Patos. Primeiro, a elevada descarga continental durante forte eventos El Niño poderia afetar negativamente o transporte passivo de juvenis de tainha para o interior do estuário, o que levaria ao declínio de juvenis na região nesse período. Segundo, as salinidades próximas a zero durante vários meses no estuário durante forte eventos El Niño poderia acarretar maior dispersão dos cardumes de tainhas adultas durante a sua migração reprodutiva para o mar, resultando em menores capturas pelos pescadores artesanais da região.

Accurate and timely information about land cover pattern and change in urbanareas is crucial for urban land management decision-making, ecosystem monitoring andurban planning. This paper presents the methods and results of an object-basedclassification and post-classification change detection of multitemporal high-spatialresolution Emerge aerial imagery in the Gwynns Falls watershed from 1999 to 2004. TheGwynns Falls watershed includes portions of Baltimore City and Baltimore County,Maryland, USA. An object-based approach was first applied to implement the land coverclassification separately for each of the two years. The overall accuracies of theclassification maps of 1999 and 2004 were 92.3% and 93.7%, respectively. Following theclassification, we conducted a comparison of two different land cover change detectionmethods: traditional (i.e., pixel-based) post-classification comparison and object-basedpost-classification comparison. The results from our analyses indicated that an objectbasedapproach provides a better means for change detection than a pixel based methodbecause it provides an effective way to incorporate spatial information and expertknowledge into the change detection process. The overall accuracy of the change mapproduced by the object-based method was 90.0%, with Kappa statistic of 0.854, whereasthe overall accuracy and Kappa statistic of that by the pixel-based method were 81.3% and0.712, respectively.